In cardiovascular research there is an urgent need for methods which would quantitatively identify: regions of high shear stresses in the flow (hemolytic factor), regions of high and low stresses at the will (atheromatous lesions), separated or reverse flow regions (thrombogenic factors), and functional (physiologic) severity of a stenosis. A computer model capable of simulating physiologically important features of blood flow in vessels would be an indispensable tool in research, education, and clinical practice. The objective of Phase II is to develop such computer software. The computer model will be able to calculate three-dimensional steady or time-dependent flow for an arbitrary vessel geometry including lesions and bifurcations, and a wide range of Reynolds numbers. In Phase I we developed a two-dimensional and axisysmmetric version of such a program. In Phase II the program will be extended to three dimensions and we plan to develop and/or upgrade: an ergonomically designed user-friendly menu system; a machine interface to read digitized arteriograms; color graphics; and a computer-aided geometry input system.